Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Dennis Wiggins]

https://au.news.yahoo.com/a/36404409/texas-teen-electrocuted-by-phone-in-bath-last-text-message/#page1

This may be a stupid question. 

Can the use of an ungrounded 2-wire extension cord trip a GFCI?

-Dennis

[Luke Mester]

Can the use of an ungrounded 2-wire extension cord trip a GFCI?

If the bathtub uses metal pipes, then yes, because they would provide an alternative path. If plastic pipes, then you could toss a 2-wire extension cord in a tub and the GFCI would not trip. I'm not sure if there's a significant risk of electrocution in that scenario or not.

[Daniel Levi]

This may be a stupid question. 

Can the use of an ungrounded 2-wire extension cord trip a GFCI?

-Dennis

Yes, remember most garden equipment (at least at consumer level) is ungrounded and that is the major market for RCD plugin adaptors. The distribution board units are essentially the same.

[John Roberts {JR}]

This may be a stupid question. 

Can the use of an ungrounded 2-wire extension cord trip a GFCI?

-Dennis

GFCI does not care about ground... If the current leaving does not exactly equal the current returning (by 5mA) it trips and disconnects power.

JR

[John Roberts {JR}]

If the bathtub uses metal pipes, then yes, because they would provide an alternative path. If plastic pipes, then you could toss a 2-wire extension cord in a tub and the GFCI would not trip. I'm not sure if there's a significant risk of electrocution in that scenario or not.

You might get away with that using pure water, but if it is contaminated with salts or acid, it will conduct and if low enough impedance trip the breaker from current draw between line and neutral in the extension cord.

My water was dirty enough (rust colored) when my heater failed, that I felt voltage when I stuck my finger into the hot water coming from the faucet... 

JR

[Dennis Wiggins]

GFCI does not care about ground... If the current leaving does not exactly equal the current returning (by 5mA) it trips and disconnects power.

JR

I appreciate your explanation.  Now that I knew what to look for, I found this Wiki explanation.

"A GFCI works by measuring the current leaving one side of a power source (the so-called "live" or "hot wire"), and comparing it to current returning on the other (the "neutral" side). If they are not equal, then some of the current must be leaking in an unwanted way, and the GFCI shuts the power off."

Silly me; I thought that it had something to do with the GROUND wire!   

-Dennis

[John Roberts {JR}]

I appreciate your explanation.  Now that I knew what to look for, I found this Wiki explanation.

"A GFCI works by measuring the current leaving one side of a power source (the so-called "live" or "hot wire"), and comparing it to current returning on the other (the "neutral" side). If they are not equal, then some of the current must be leaking in an unwanted way, and the GFCI shuts the power off."

Silly me; I thought that it had something to do with the GROUND wire!   

-Dennis

There is a separate class of protection devices that measures current leaking into a line cord ground. (I haven't seen them used with consumer gear, most of which no longer even use grounds).

When I designed my super safe muso protector, I not only included GFCI, but I had a secondary circuit that would disconnect if it measured more than 5 mA flowing in the ground lead, since a backline GFCI will not prevent a shock hazard coming from an energized FOH console ground.

Of course a GFCI on both FOH and Back line will be adequately protective (and cheaper than my exotic gadget).

JR

[David Allred]

Silly me; I thought that it had something to do with the GROUND wire!   

-Dennis

Silly nomenclature.  Everyone knows that it should be a GTFMDFCI.  "Greater Than 5 Millivolts Differential Fault Circuit Interrupter". 

[David Allred]

https://www.youtube.com/watch?v=6Dd6_TghcE0

Discusses possible causes then updates with actual report from family.

[Lyle Williams]

I have great respect for the family going public with the picture.

A dreadful time for them, but the safety lesson will now be learned by many more.

[ProSoundWeb Community]